Method of making heating elements



June 6, 1933. E. L. WIEGAND 1,913,355

METHOD OF MAKING HEATING ELEMENTS Fild March 2 1, 195o /f ff /4 PatentedJ une 6,y 1933 PATENT oFr-'lcE EDWIN L. WIEGAND, OF PITTSBURGH,PENNSYLVANIA."

` METHOD or MAKING HEATING mEMENTs i Applicationled March 31, 1930.Serial No. 440,307.

This invention relates to an improved method of producing heatingelements and has for its object to secure greater efficiency linmanufacture and produce a superior product. Other and more specificobjects will appear as the description proceeds. In the drawing, Fig.Lis a perspective View showing a core for the heating element and themethod of Winding a'resistor thereon and securing the same thereto;Fig.'2 is a perspective view of a pair of slabs of friablenon-combustible electrical insulating material; Figs. 3, 4 and 5 aresectional views showing thecore of Fig. 1 introduced between slabs offriable material, the' different figures showing variantV forms ofslabs; Fig. 6 is a sectional View showing the assembly of F' 3introduced into a tubular sheath; Fig. is a sectional view showing theheating element in the stage of Fig. 6 in the die pre aratory to finalforming pressure; and ig. 8 shows thedie in final .pressureexerting'position.

In carrying out my improved process I provide a plate 10 which mayconsist of mica or other suitable rigid non-combustible electricalinsulating material. Upon this plate is wound a helical resistor 11 madeof any suitable material, such as is generally used for this purpose inthe art. This resistor is secured as at 12 to a terminal 13 by passingthrough an opening drilled in Vthe plate 10 and being electricallyconnected to the terminal in any suitable manner. A pair of slabs 14 areprovided to receive the core shown in Fig. 1 therebetween. These slabsmay be made of any suitable refractory linsulating material and may beproduced by causing adherence of the particles together by pressure orby the use of a suitable binder in connection with the use of the moldor in any other manner known to those skilled in the art. The slabs 14may be formed with angular portions 14a extending at right angles ateach v end of each slab, as shown 1n Fig. 3, or the overhanging portionsmay be omitted and the ends simply extended beyond the edge of the core,as shown in Fig. 4, or overhanging portions 14b may be provided on-oneof the slabs l'and the other slab left straight, as shownl in c Fig. 5.In all cases, however, a sufiicient amount of material is containedinthe friable slabs 14 to admit of complete filling of the sheath 15 whenfinal pressure is applied.

After the core of Fig. 1 is introduced betweenthe slabs of Fig. 2, thisassembly is inserted intoa sheath 15 in the manner shown in Fig. 6. Itwill be observed that the sheath .l5 is of such a size as to receive theslab and core assembly easily yet without excess of space. The crosssectional area of the slabs, the core and the sheath will, of course, beso proportioned that when the assembly is pressed to desired thickness,the desired compacting of the refractory material l will be obtained. u

After the element shown in Fig. 6 is assembled, the same is placed in adie 16 which is provided with'end 'stops 17 to prevent -extrusion'fromthe ends of the refractory materialand these stops are provided withslotsto receive the terminals 13. The movable die 18 is now brought downlaterally of the sheath and the desired final pressure is applied,resulting in a flattening of the sheath to the thickness shown in Fig. 8and very high compacting of the refractory material around l the core.It will be understood that when the pressure is applied to the assemblyof Fig. 6, the friable slabs 14 will be crushed and lill up all thespace between the core and the' sheath.

By the use of this method I amenabled to avoid the necessity of pouringthe refractory material around the core which necessitates setting upthe sheath and core on end and some means to hold them in properrelation l to each other while the material is being poured in. I alsosecure a more uniform density of refractory material in this way than ispossible when the same is poured into the sheath around thefcore. Theapparatus involved is 'also somewhat simpler'and it is possible tomanufacture the slabs of refractory material at one place and transportthem already formed to the place where the heating elements aremanufactured instead of transf porting the refractory material inpowdered orm.

While I have shown'and described certain illustrative embodiments of myinvention, I Wish it understood that I ,am not limited to suchembodiments but may carry out my invention in a number of variant formswithinthe scope of the appended claims.

Throughout the specification and claims I have used the term resistor toinclude a resistor alone or self-supported or a resistor with itssupport.

Having tlius described my invention, what I claim is:

1. A method of producing electrical resistor heating elements whichconsists in positioning a resistor upon a core, covering the resistorand core by placing thereover a plurality of large slabs of friable,non-combustible, electrical insulating material, introducingsaid coreand slabs into a sheath and'applying pressure thereto to thoroughlycrush said slabs and to compact said-insulation material about theresistor and core.

2. A method of producing electrical resistor heating elements whichconsists in positioning a resistor upon a core, covering the resistorand core by placing thereover a plurality of large slabs of electricalinsulating material, introducing said core and slabsy into a sheath andapplying pressure thereto to thoroughly crush said slabs and to compactsaid insulation material about the resistor and core.

3. A method of producing electrical resistor heating elements whichconsists in positioning a resistor upon a core, covering the c resistorand core by placing on opposite sides thereof a plurality of slabs ofinsulatingmaterial, then enclosing the slabs, resistor and core within asheath and compressing the same to thoroughly insulate the resistor andto compact the insulating material thereabout.

4. A method of producing electrical resistor heating elements whichconsists in p0- sitioning a resistor upon a core, covering the resistorand core by placing on opposite sides thereof a plurality of 'slabs ofinsulating material, then enclosing the slabs,v resistor and core withina sheath and compressing the same to thoroughly insulate the resistorand to compact the insulating material thereabout, said slabs being ofreater width than said core whereby in theial form said core may beentirely surrounded by the insulating material.

5. A method of producing electrical resistor heating elements whichconsists in positioning a resistor upon a core, covering the resistorand core with a plurality of slabs of insulating material shaped toprovide a recess therebetween adapted to receive said core with resistorthereon, then introducing the resistor, core and slabs into a-sheath andlaterally compressing said sheath to crush said slabs and thoroughlycompact the insu lation material aboutthe resistor.

6. A method of producing electrical resisl tor heating elements whichconsists in placing a resistor between a plurality of large slabs ofriablc non-combustible electrical insulating material, introducing saidslabs with resistor therebetween into a receptacle and applying pressurethereto to thoroughly crush said slabs and to compact said insulationmaterial about the resistor.

7. A method of producing electrical heating units which consists inpositioning a relatively long resistor sidewise between relatively largeslabs of friable non-combustible electrical insulating material,introducing said slabs with the resistor therebetween in a sheath andapplying pressure thereto to thoroughly crush said slabs and to compactsaid insulationmaterial about said resistor.

In testimony whereof, I hereunto aflix my signature.

EDWINy L. WIEGAND.

